1. Field of the Invention
The present invention relates to thermal air flowmeters which measure a flow of gas (air), and more particularly to a thermal air flowmeter suitable for detecting a flow of air sucked into the engine of an automobile.
2. Background Art
Examples of conventional flowmeter for air sucked into the engine of an automobile include: a system, as described in JP Patent Publication (Kokai) No. 2003-185481 A, which detects a heating control current value of a heat-generating resistor and converts the value into a flow of air; and a system which detects, as a temperature difference signal, a thermal effect on temperature-sensitive resistors arranged upstream and downstream of a heating register and captures the signal as a voltage of a bridge circuit.
Further, JP Patent Publication (Kokai) No. 11-351938 A (1999) proposes an approach which applies separate corrections to rising and falling characteristics with respect to an output response appearing in a thermal air flowmeter and thereby reduces a response difference occurring in the detection element.